Non-stoichiometric titanium compound-carbon composite, method for producing same, negative electrode active material and lithium ion secondary battery

Patent metadata

Field	Value
Publication number	US-10276863-B2
Application number	US-201514963896-A
Country	US
Kind code	B2
Filing date	Dec 9, 2015
Priority date	Jun 14, 2013
Publication date	Apr 30, 2019
Grant date	Apr 30, 2019

Abstract

A composite material including a carbon-containing material and a non-stoichiometric titanium compound shown by a chemical formula of Li4+xTi5−xO12, where x is in a range of 0<x<0.30, the composite material including at least one composite particle that has a core portion including the non-stoichiometric titanium compound and a mixed layer formed on a surface of the core portion, the mixed layer including non-stoichiometric titanium compound and carbon, and having an atomic ratio of titanium and carbon in a range of Ti/C=1/50 or more.

First claim

What is claimed is:

1. A non-stoichiometric titanium compound-carbon composite material shown by a chemical formula of Li 4+x Ti 5−x O 12 , where x is in a range of 0<x<0.30, comprising:
at least one composite particle that has a core portion comprising the non-stoichiometric titanium compound and a mixed layer formed on a surface of the core portion,
the mixed layer comprising non-stoichiometric titanium compound and carbon, and having an atomic ratio of titanium to carbon (Ti/C) in a range of from 1/50 to 1/2,
wherein the mixed layer exists over an entire surface of the core portion, and
the mixed layer has a thickness of 1 nm or more and 100 nm or less.

2. The non-stoichiometric titanium compound-carbon composite material according to claim 1 , wherein a specific surface area thereof determined by BET method is 20 to 100 m 2 g −1 .

3. The non-stoichiometric titanium compound-carbon composite material according to claim 1 , wherein the composite particle has an average particle diameter of 20 μm or less.

4. The non-stoichiometric titanium compound-carbon composite material according to claim 1 , wherein the thickness of the mixed layer is 20 to 100 nm.

5. The non-stoichiometric titanium compound-carbon composite material according to claim 1 , wherein a variation of a thickness of the mixed layer is ±20% of an average thickness of the mixed layer.

6. A negative electrode active material comprising the non-stoichiometric titanium compound-carbon composite material according to claim 1 .

7. A lithium ion secondary battery comprising a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolyte, wherein the negative electrode comprises the negative electrode active material according to claim 6 .

8. A method for producing the non-stoichiometric titanium compound-carbon composite material according to claim 1 , comprising:
performing dissolution of components which are a hydrophilic polymer, a lithium salt, and a titanium alkoxide in an aqueous solvent by adding the components in the solvent and dissolving the components while dispersing the components by agitation;
performing formation of a precursor material by spray-drying a solution obtained by the dissolution; and
performing firing of the precursor material under a reduced atmosphere or inert atmosphere at a temperature of not lower than 600° C. and not higher than 900° C.

9. The method of claim 8 , further comprising preliminary firing the precursor material under a reduced atmosphere or an inert atmosphere at a temperature of not lower than 300° C. and lower than 600° C. before the firing.

10. The method of claim 8 , wherein a polyvinyl alcohol is used as the hydrophilic polymer.

11. The method of claim 10 , wherein a viscosity average polymerization degree of the polyvinyl alcohol is 200 to 5000.

Assignees

• Kuraray Co
• Incorporated National Univ Iwate Univ

Inventors

• Wakui Takashi
• Fujiwara Naoki
• Shimazumi Yuhi
• Yamamoto Yoshio
• Ui Koichi
• Kadoma Yoshihiro

Classifications

• H01M4/587

  for inserting or intercalating light metals · CPC title

• C01G23/005

  Alkali titanates · CPC title

• H01M2220/30

  Batteries in portable systems, e.g. mobile phone, laptop · CPC title

• C01P2004/61

  Micrometer sized, i.e. from 1-100 micrometer · CPC title

• C01P2006/40

  Electric properties · CPC title